[order] PROCELLARIIFORMES | [family] Procellariidae | [latin] Pterodroma sandwichensis | [authority] Ridgway, 1884 | [UK] Hawaiian Petrel | [FR] Petrel des Hawaii | [DE] Hawaii-Sturmvogel | [ES] Petrel Hawaiano | [NL] Hawaii-stormvogel
Genus Pterodroma, Pseudobulweria and Aphrodroma are also knwon as the Gadfly Petrels. They vary in size from rather small birds such as the Cookilaria-species, measuring about 26 cm, to the much larger and robust representatives of this group like the White-headed Petrel with an overall length of about 43 cm. Their plumages also vary a great deal from species to species; from completely black to light grey mantles and pure white bellies, and with different color phases within species. One feature shared by all of them is the black bill of which the shape also shows much variation. Some species are extremely rare and restricted to a very limited area, other are abundant and wander widely or have unknown pelagic ranges.
The group of the Gadfly Petrels counts over 35 species, mainly from the Southern Hemisphere. There are three genera: Pterodroma with about 30 species, Pseudobulweria counting four and Aphrodroma with only one. Many authors have tried to classify the large number of species of this group and to determine their relationships. This has resulted in a division in several subgenera and the grouping of several species which are considered to have a more or less close relationship. The taxonomic discussion has not come to an end yet: new species have been added or split recently and probably will be in the near future.
Large, dark grey-brown and white petrel. Dark black-brown cap extends below eye and also forms half collar across upper breast. Remainder of head white, forehead conspicuously so. Upperparts, including upperwing and tail, darkish grey-brown without “M” pattern. Many, but not all, show white patches on side of rump. White underwing with narrow black trailing edge, black tip, broad black edge between primaries and carpal joint. Band extends weakly towards centre of wing from joint. Compared to Juan Fernandez Petrel P. externa and White-necked Petrel P. cervicalis darker, with more extensive cap, darker back, lacking “M”, and different underwing. Compared to Galapagos Petrel P. phaeopygia lacks black forehead markings
Listen to the sound of Hawaiian Petrel
Copyright remark: Most sounds derived from xeno-canto
recorded by Todd Mark
Pacific Ocean : Central. Pterodroma sandwichensis ranges in the central Pacific and breeds on the Hawaiian Islands (USA), where an estimate, supported by pelagic surveys, put the total Pacific Oceanpulation at 19,000 (range 10,600-34,400), including a best estimate of 4,500-5,000 breeding pairs. However, the discovery of previously unknown colonies in 2006-2007 may bring the total Pacific Oceanpulation closer to the upper estimate of 6,500-8,300 pairs10. The observation of birds’ movements by radar suggests that the total number on Maui exceeds the current estimate of 1,800 individuals. Approximately 1,200 burrows are known in Haleakala Crater, Maui, although not all of these are used every year17, and two small colonies are present in the West Maui Mountains.
On Maui, Mauna Kea and Mauna Loa, nesting takes place mainly between 2,000 and 3,000 m, in lava cavities with little vegetation nearby. Elsewhere, for example West Maui17 and Kaua`i, it nests at lower elevations, amongst dense shrubs and ferns, or in native grasslands with bracken. On Haleakala, Maui, birds nest in rock crevices and tunnels that are over 0.5 m deep, often exceeding two meter.
Generally, the nest chamber can be from one to nine meter deep. Pairs nest in cavities in the volcanic terrain, in burrows beneath rocks or at the base of clay cliffs. At lower altitudes, they excavate burrows or nest in cavities often at the base of trees, although many burrows on Lana`i are not at the base of trees. It takes each bird five to six years to reach maturity. Most eggs are laid in May and June, with most young fledging by December. Pairs mate for life. The female lays only one egg per year. If this egg fails, the female will not re- nest. Male and female share in egg incubation. Incubation is about 56 days. Male and female share in feeding of young. Young are fed until they are double the size of the parents. Parents will then abandon the young, around September of each year, and leave the nesting colony until the next season. Once the young birds lose enough weight, they leave their nest for the open ocean. These young fledglings leave their nests at night, in October. Scientists believe that ‘Ua’u use the stars to navigate. Young birds will remain at sea for 3 to 6 years.
The diet comprises mostly fish and squid, with squid constituting c.50-75% of the food ingested. The species usually forages in mixed species flocks, typically over schools of predatory fish species.
copyright: Jill Lippert and Darcy Hu
This species qualifies as Vulnerable because it has a very small breeding range. It is known from five locations in the main Hawaiian islands, and the future of at least two are in jeopardy (Mauna Loa and West Maui). Its limited distribution and declines primarily result from predation by introduced mammals and urbanisation.
The species was eliminated from many islands in the archipelago, and it may already have been restricted to its current breeding range when Europeans arrived. Nesting habitat has since been lost to urbanisation and degraded by feral goats and pigs. Nest burrows are trampled by feral goats, mouflon sheep and potentially chital Axis axis. The most serious current threat is predation by introduced vertebrates including feral cats, Barn Owls Tyto alba, rats, dogs, pigs and the small Asian mongoose.
Probably disperses widely throughout Pacific, perhaps N towards boreal zone.